Rulers have long been known for measuring and creating straight lines. With reference to FIG. 1, a traditional ruler 10 includes a length having gradations or distance markings 12, 14, or 16 along an edge 20 to measure a structure, such as a planar surface 21 of a piece of paper or wood 22. Because the gradations are not always precise enough, or have a poorly matched system to the structure (e.g., inches, centimeters, etc.), it is sometimes difficult for users of the ruler to know an exact length of the structure. In this case, it is difficult to know a width W of the paper or wood because edge 25 falls somewhere between 3 and ¾ inches and 4 inches.
While many precision rulers or other measuring tools often have a multiplicity of dimensions to avoid this problem, a problem exists in the art of rulers made for school-aged children. That is, basic rulers for children in the U.S. often have a few simple gradations, regularly in inches, that do not have enough distance markings to accurately measure many structures or objects. While this does not present a great problem as children advance in their studies, and become more masterful with measurements and mathematics, it can be a daunting proposition for younger students as they first learn how to use rulers and other measuring tools. It can also be a problem in that early students have little, if any, feedback regarding the correctness of their measurements.
Accordingly, a need exists in the art of rulers, especially basic rulers for school-aged children, to provide measurement capability in the absence of sufficient gradations. There is also a need to provide feedback regarding correctness to stimulate learning in adolescent students. Naturally, any improvements along such lines should further contemplate good engineering practices, such as relative inexpensiveness, ease of implementation, low complexity, etc.